Thaw shrimp, if frozen. Peel and devein shrimp, leaving tails intact if desired. Rinse shrimp; pat dry with paper towels. In a medium saucepan heat 2 teaspoons of the oil over medium-high heat. Add couscous; cook and stir for 3 to 4 minutes or until lightly browned. Add the water. Bring to boiling; reduce heat. Simmer, covered, for 8 to 10 minutes or until couscous is tender. Remove from heat.
In an extra-large nonstick skillet heat the remaining 2 teaspoons oil over medium-high heat. Add shrimp; cook and stir about 3 minutes or until shrimp are opaque. Stir in cooked couscous, salad dressing, salt, and pepper. Cook and stir for 2 to 3 minutes more or until heated through. Stir in mango. Sprinkle with queso fresco and parsley.